A recent patient has reminded me of a moment in my life that still makes me laugh. I was trekking in Nepal with my wife and two others, one another doctor. After 8 days of trekking we had made it to Jomsom up the Kali Gandaki valley where the doctor declared she had run out of money. Really?! There is very little to spend money on along this trek, however it transpires most of her money had gone on rare Tibetan jewellery made from Yaks teeth. Her husband’s face said it all! Our guide later confessed there were no Yaks here as the altitude was too low and they cannot breathe...he thought the necklace was more likely to be buffalo teeth! There are no trading standards when it comes to buying from very astute Tibetan lady traders...fools beware.

Anyhow back to the patient, he was in his 30s and had a long history of dental problems, with multiple fillings and extractions. For several months now he had had an ongoing infection of his jaw and had received multiple courses of antibiotics. He had been referred by his dentist to the maxillofacial surgeons who drained the abscess and prescribed a week of Metronidazole but the abscess had reoccurred. Further drainage was performed and Co-amoxiclav was tried and failed. The maxillofacial surgeons planned to carry out further surgery and were calling to find out what antibiotics to give. The Registrar explained to me that “none of the swabs sent to the laboratory had grown any bacteria”. I said “umm that problem can occur if the correct microbiological samples are not taken”. There was a pause on the phone.

Actinomycosis...funny what someone will make as a cake!

​I explained that swabs were never the ideal specimen to send and that pus or tissue should always be the preference when sending samples to the laboratory from an operative site. “Oh OK...” said the Registrar...you could almost hear how he was trying to think of a delicate way to say this to his Consultant! ...I go on...“and when several months of various antibiotics have been given there is a high chance that large swathes of bacteria have been almost eradicated and that is why the results are inconclusive”. I continue “if the patient can be off antibiotics for at least two weeks prior to the next drainage it will give us the best chance of trying to grow any bacteria”.

On the day of the surgery a sample of pus arrived in the laboratory and the Gram’s stain showed long beaded Gram-positive bacilli (just like a Yak-tooth necklace!). The appearance was distinctive and I called the surgeons and suggested the patient had orocervicofacial actinomycosis. The treatment is IV Benzylpenicillin, a prolonged course is recommended, and 6-12 months might be required. I could tell the maxillofacial surgeons were a bit sceptical at first but the patient made good progress. After 10 days distinctive colonies had appeared on culture and the laboratory was able to confirm the diagnosis. The surgeons were finally convinced.

So what is actinomycosis?Actinomycosis is the term used for infection with bacteria from the group known as Actinomyces spp. These bacteria are long filamentous anaerobic Gram-positive bacilli. They contain some mycolic acid in their cell walls (like Mycobacteria) which makes them a little difficult to stain using Gram’s stain; as a result they often look a little beaded and might be mistaken for Streptococcus spp. by the inexperienced observer. The most common type of Actinomyces spp. to cause human disease is A. israelii.

Actinomyces spp. are part of the normal flora of the upper respiratory, gastrointestinal and genitourinary tracts. They are not naturally invasive, but when the normal mucosal barriers are damaged they can invade and establish infections. Actinomycosis is therefore an endogenous infection.

Actinomycosis is a difficult infection to diagnose because the bacteria are very slow growing and cause little inflammatory response. It is usual for actinomycosis to be initially misdiagnosed as either malignancy or tuberculosis, which are more common, the correct diagnosis only being made once surgical samples have been obtained. It is estimated that the incidence of actinomycosis in the UK is approximately 1 in 150,000 admissions per year. Actinomycosis does not appear to be more common in the immunocompromised.

Infection with Actinomyces spp. is said to occur more frequently in men than women, although the exception to this is pelvic actinomycosis where the main risk factor is the presence of an intrauterine contraceptive device (IUCD) for more than 2 years. If the patient had pelvic actinomycosis due to an IUCD then the IUCD should be removed, and other forms of contraception advised.

How does actinomycosis present?There are four main clinical forms of actinomycosis:

Orocervicofacial – 50% of cases, following dental manipulation or trauma or as a result of poor oral hygiene, presents with fever, swelling of the perimandibular soft tissues and eventually sinus formation

Thoracic – 15-20% of cases, following aspiration of oropharyngeal flora, oesophageal perforation or haematogenous spread, presents with fever, cough, shortness of breath and chest pain usually in patients with chronic obstructive pulmonary disease (COPD), haemoptysis or sinus formation can also occur

Central nervous system (CNS) – rare but serious form of actinomycosis resulting from haematogenous seeding of the CNS or occasionally direct extension from orocervicofacial actinomycosis, leading to abscess formation and sometimes meningoencephalitis, mimics other causes of space occupying diseases e.g. malignancies

How is actinomycosis diagnosed?The most important aspect of the diagnosis of actinomycosis is clinical suspicion. There are some features which can alert the clinician to a possible diagnosis of actinomycosis in the context of a mass lesion including:

The presence of sinus tracts

Erosion through tissue planes

Relapse after initial response to short courses of antibiotics

Clinical suspicion ensures that the correct histopathological and microbiological tests are performed on any clinical specimens. The most appropriate clinical specimens are pus and tissue; swabs are not ideal as they cannot be readily Gram’s stained. Actinomyces spp. often produce sulphur granules in pus (hard lumps containing the colonies of bacteria) these sulphur granules can be crushed and then stained using Gram’s stain to show typical Gram-positive bacilli. Microscopy is quicker, taking only a few hours, and is more reliable than culture (culture requires 2-3 weeks of incubation at 37oC on selective agar) but even then up to 50% of these microorganisms fail to grow.

It is common for Actinomyces spp. to be seen histologically on cervical smears, and over the years I have had many calls from colleagues asking about the clinical significance of seeing these bacteria. My advice is that unless there is a specific reason to suspect pelvic actinomycosis (e.g. clinical symptoms or an unexplained pelvic mass) then they should be considered as normal flora and nothing more needs to be done.

How is actinomycosis treated?Antibiotics are the main stay of treatment for actinomycosis. Traditionally prolonged courses of 6-12 months have been required, with the initial phase being 2-6 weeks of high-dose IV Benzylpenicillin followed by PO Penicillin V. There are now case reports of patients being successfully treated with other beta-lactams such as Ceftriaxone, Meropenem, Imipenem and Piptazobactam. Patients who are allergic to beta-lactams can be treated with Doxycycline, Minocycline, Clindamycin or Erythromycin.

There are recent case reports that suggest that not every patient requires 12 months of treatment, especially if the bacterial burden is reduced by surgical drainage. In particular there has been some success with 6 weeks of antibiotics for orocervicofacial and thoracic actinomycosis where the infection has not been extensive and surgical drainage has occurred. It would seem prudent that if short course therapy is attempted the patient should be followed up for at least 1 year, both clinically and with further radiological imaging, to ensure the infection does not reoccur.

The patient in the case above was given 2 weeks of IV Benzylpenicillin followed by 6 months of oral Penicillin V, as his swelling was slow to resolve. Eventually he made a full recovery and the swelling and abscess did not reoccur. Whether the Yak’s teeth fell out due to actinomycosis, I don’t know but it’s possible and whether the Yak tooth necklace was ever found to be genuine I also do not know. I am not an expert on teeth or jewellery, however the comment made to my wife by a Tibetan lady trader was “you’re not a gullible as your friend...” might enlighten you to the answer.